Typo in "fnctl" / "fcntl"

[geofft]

I noticed that libstd/sys/unix/fd.rs has this code:

    #[cfg(target_env = "newlib")]
    pub fn set_cloexec(&self) {
        unsafe {
            let previous = libc::fnctl(self.fd, libc::F_GETFD);
            let ret = libc::fnctl(self.fd, libc::F_SETFD, previous | libc::FD_CLOEXEC);
            debug_assert_eq!(ret, 0);
        }
    }

I'm pretty sure that should be fcntl ("file control"), not fnctl: the call is consistent with the use of fcntl on other UNIXes, and as far as I can tell, the newlib git repo defines fcntl but not fnctl. This would need to be fixed in both libstd and liblibc.

But there's an explicit mention of this code in the PR introducing it (#29289), and I'm sort of surprised that this would link if it were misspelled, let alone work, so maybe I'm missing something? If this is correct, a comment would be nice. :)

cc @DiamondLovesYou

[DiamondLovesYou]

You're right, oops (PNaCl isn't testable yet within Rust proper, so I didn't catch it!).